Body of this scale-worm small, tapering posteriorly. Dorsal surface smooth, ventral surface papillate in the anterior region.
Prostomium triangular with a median antenna, a pair of palps and a papilla-like facial tubercle, two pairs of eyes separated or just touching.
First segment achaetous with a pair of papillate dorsal and ventral tentacular cirri in cirrophores which extend to ensheath the base of the palps.
Scales overlap but do not cover the anterior dorsal surface when the proboscis is retracted. They occur on segments 1, 3, 4 and 6, then alternately to the 22nd and then on all segments. The first pair are round, the rest oval to kidney-shaped. All scales have short annulated papillae on the margins and surfaces smooth. Two ctenidial cushions attached to the dorsal surface of notopodia appear on the 2nd segment and three appear on all remaining segments.
Notopodia are small mounds with chaetae arranged dorsally in a semicircle. Notopodial chaetae of two kinds: 1) fine capillaries; 2) geniculate capillaries. Neuropodia projecting beyond notopodia with long papillae and chaetae in bundles. Neuropodial chaetae with stout blades, unidentate tips and shafts spinose or smooth (P. inornata-detail).
Up to 8 mm for 68 chaetigers.
Littoral to shallow sublittoral.
Arctic, North Pacific, Atlantic up to Mediterranean, Black Sea, English Channel, North Sea, Skagerrak, Kattegat, Öresund and Belts up to mid-Baltic Sea, South Africa.